Hi!
His water temp at the moment is 76-77°f and his basking temp is 93-94°f, which I think gives a 10°c difference when converted (sorry, I normally work in °f). His water is normally 73-74°f, but for some reason it has jumped up a bit in the last week and won't go down again, and that is with the heater unplugged, so it must be the weather. My thermometer has been acting up recently though, so I have ordered a new one in case I am getting bad readings.
During my panicked googling spree yesterday, I remember reading something that said that Map turtles like a higher basking heat, more into the high 90's, so I might check that out, but he normally basks quite a bit with the temps as they are, just not for the last 2 weeks. I'm not sure if that is because of the warmer water temp or because he is a bit more skittish than usual due to being taken out twice a day for Povidone treatment.